The proposed investigation is directed toward the study of collagen loss during periodontal disease due to collagenase activity. Specifically, a number of agents and several cell types will be tested for their ability to induce active collagenase in cultured cells. Agents to be tested will include plaque extracts, Dilantin sodium, dexamethasone, thyroxine, parathormone, prostaglandins and endotoxin. Cell types to be tested include T lymphocytes, B lymphocytes and mast cells. Cells to be cultured include gingival fibroblasts and pulmonary macrophages. Experiments will be conducted to determine whether the appearance of active collagenase in cell cultures results from the induction of collagenase. Another series of studies will be carried out to purify and characterize the collagenase inhibitor found in the culture media of gingival fibroblasts.